VSTHRD103 regression: recommends ThrowsAsync for synchronous xUnit assertions #1661

VSTHRD103 again recommends xUnit's Assert.ThrowsAsync when the delegate under test is synchronous. This was previously tracked and fixed in #61.

With Microsoft.VisualStudio.Threading.Analyzers 18.7.115, code shaped like this is flagged when it appears in an async test method:

Assert.Throws<FormatException>(() => ParseInvalidValue());

The suggested ThrowsAsync API is not semantically appropriate because the operation under test completes synchronously and does not return a Task. Applying the suggestion requires wrapping the synchronous operation in an artificial completed task.

Expected: VSTHRD103 should not report synchronous xUnit assertion calls whose delegate does not return a task.